Readily configured and reconfigured structural trusses based on tetrahedrons as modules

ABSTRACT

Truss structures assembled from modules comprising one hinge link, four spacer links and four apex joinders, one at each end or each hinge link. The second hinge link to complete a tetrahedron is missing from the module, and is provided by the hinge link of a next in line module so as to provide a series of joined tetrahedrons. When the strut is assembled, the apex joinders enable the strut to be formed into a wide variety of shapes.

FIELD OF THE INVENTION

Structural trusses useful as support structures which are readilyassembled from tetrahedron modules into various configurations, and canreadily be reconfigured and dismounted. The modules themselves occupyminimal bulk volume and are nestable, to reduce costs of shipment.

BACKGROUND OF THE INVENTION

Most common structural trusses include in-plane series of rigidthree-link modules- rigid triangular elements. Others includecombinations of rigid links and cable links. These have in commonlimitations on the ultimate configuration of the truss, especially whencurvatures and twists are involved.

In addition, when they are shipped, they are usually in sections thatinclude a large hollow volume. In effect the user ships a considerableamount of air. When freight is charged by volume rather than weight, thecost to ship them compared to the cost of shipping a group of nestedmodules is considerable. When shipped by truck, fewer trucks arerequired to move the elements major structures theatrical field wherelights and equipment must be supported in various configurations, whichconfiguration (geometry) must often be changed quickly, for example whenmoving from a stage of one configuration to one of a differentconfiguration. These systems must often be shipped by air or truck whenthe production moves to another location, and changed to a differentarrangement during the same production.

Versatility of available configuration is another advantage of thisinvention. Depending on the job, an arch, a complicated curvature (bothin-plane and out-of-plane), trussed and straight trusses are availableusing the same equipment. Even totally circular rings can be formed.Many attainable configurations are not available elsewhere at all, andwhen available they involve large costs.

It is an object of this invention to provide a truss composed ofinterconnected modules whose ultimate configuration can readily becalculated and built, and which when dismantled can be shippedeconomically. It is structurally sound, and economical to make. In useit has versatility of shape, and is able to support auxiliary equipmentsuch as lights and rails.

In addition this invention can provide structures intended to bepermanent or to remain in place for a considerable amount of time.

BRIEF DESCRIPTION OF THE INVENTION

This invention provides a module to make a variable geometry truss whichcan readily be configured and reconfigured, dismounted, and economicallyshipped. It is based on the tetrahedron which is a stable and rigidstructure. The truss is formed by joining contiguous modules at hingelinks.

The module itself includes a hinge link, four spacer links, and fourapex joinders. A complete tetrahedron would have one more hinge linkbetween apex joinders, but it is missing one. This is for the purpose ofinserting the hinge link of a “next” module into that open spacing tocomplete the tetrahedron structurally and to provide for a hingingmovement at the junction.

The space left open by the missing link enables a similar module to benested into its neighbor, thereby greatly reducing the bulk of themodules for shipment.

Auxiliary equipment can be and immediately will be attached to thetruss.

The above and other features of this invention will be fully understoodfrom the following detailed description and the accompanying drawings,in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1-7 are schematic illustrations of the invention to present thegeometric relationship of its parts.

FIG. 1 is a top view of the basic structure of a module according to theinvention;

FIG. 2 is a view taken perpendicularly to lines AB in FIG. 1;

FIG. 3 is a top view of FIG. 2;

FIG. 4 is a right-hand side view of FIG. 3;

FIG. 5 is a left-hand side view of FIG. 3;

FIG. 6 is a plan view of a strut according to the invention;

FIG. 7 is a side schematic view showing an angular relationship betweentwo contiguous modules, and their associated sections;

FIG. 8 is a structural view similar to FIG. 2, showing physical as wellas geometric features;

FIG. 9 is a side view showing a group of nested modules;

FIG. 10 is a plan view of one part of a node according to the invention.

FIG. 11 is a plan view of a nesting part of the node; and

FIG. 12 is a fragmentary cross-section taken at line 12-12 in FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION

This invention utilizes a rigid tetrahedron shape which in its minimummodule includes four apexes (“apex joinders” herein), and only fivedihedral edges. In contrast, a complete tetrahedron includes sixdihedral edges, not just five. The dihedral edges are formed by rigidlinks which are rigidly joined in groups of three at each of the apexjoinders. The omission of one of the links is at the heart of thisinvention, because in an extended configuration it is provided by thehinge link of a next tetrahedron which thereby forms a hinge jointbetween two contiguous tetrahedrons, completing the structure.

For convenience in disclosure and recognition, the first group of FIGS.1-7 is for the purpose of defining the basic structure.

The ultimate objective of this invention is to form a plurality oftetrahedrons at specific nodes (“apex joinders” herein) to provide ahinged-together string of these structures whose ultimate path can bedetermined by adjusting the angular relationships of contiguoustetrahedrons at axes where the hinge link of one tetrahedron “filled in”for a virtual, missing link of its neighbor. These hinge joindersalternately occur at normally-related skew events.

FIG. 1 is a top view of a regular tetrahedron resting on one of itsfaces. For convenience in disclosure, it and the other Figs. willuniformly use the designations in this Fig. for the disclosure of theinvention.

Tetrahedron 20 is formed by six links to provide four dihedral edges andapex joinders. Ultimately, the relationship between axes defined bypairs of apexes will be shown to be critical to the invention.

Apexes A, B, C and D are formed at the rigid intersections of six rigidlinks. As will be shown, one of these links is missing from each module.In a completed truss, the missing link is supplied by a correspondinglink of a next-in-line tetrahedron. The missing link is shown in dashedlines for purposes of this invention

FIG. 2 is supplied to provide a disclosure more useful to the reader. Inthis Fig, links AB and CD are referred to as “hinge” links.

The links interconnecting the hinge links are called “spacer” links. Inthe conduct of this invention, the spatial relationship between thehinge links is basic. The function of the spacer links is structurallyto hold them in their relative position. A function of all of the linksis to provide adequate compression and tension strength for a truss thatcomprises a hinged-together plurality of these tetrahedrons.

Consider the spatial relationship between hinge links AB and CD. FIG. 2is an elevation view in which link AB is vertical and in the drawingsheet. It is displayed in solid line. As shown in FIG. 3, which is a topview of FIG. 2, link CD is spaced from link AB. Link CD is shown indashed line, because the module does not-include it. Of most importanceis that the axes AB and CD are skew. They are not parallel, but in sideview they are normal, but do not meet. CD will be normal to a planethrough its mid-point that includes AB. This is of great consequence tothis invention, because as shown in FIG. 3 there is a directional vectorV, that bisects the dihedral angle. It determines the direction of astrut assembled by the insertion of the link AB of one module into thegap CD of its neighbor.

Further in detail, spacer links AC and AD are a pair structurally joinedto apex joinder A. Spacer links BC and BD are a pair joined to apexjoinder B. One member of each of these pairs is structurally connectedto apex joinder C (spacer links AC and B), and the other spacer links ADand BD are connected to apex joinder D.

Links AC and BC converge to apex joinder C, and links AD and BD convergeto apex joinder D.

The spacing between apex joinders C and D is unobstructed. As will laterbe shown, these face each other, while apex joinders A and B face awayfrom each other. This enables the parts of the apex joinder to be placedtogether and enables rotation around this common axis.

The spacing between apex joinders C and D is shown in dashed lines. Thisspacing is open and unobstructed. It is open to receive hinge links ABfrom another module, and enable the modules to be nested when notattached to another module.

FIGS. 6 and 7 are schematic showings of joinders of three modules, andthe capability of the device to assume a variety of configurations. InFIG. 6, three modules 21,22,23, are joined at hinge joints 24 and 25.The letter identifications in FIGS. 1-5 are continued for convenience.The successive links with the same letter also bear a number identifyingthem as being part of modules 21,22 and 23.

Here, notice that A1B1 and A3B3 are normal the plane in this view, andthat A1B1 and A3B3 are parallel to each other. A2B2 (C1D1) and C3D3 areparallel and in the plane of the view. This is an alternating featurewhere the illustrated faces of the tetrahedron all lie in the sameplane. As will be shown, this relationship can be changed to provide fordifferent shapes, including twists. FIG. 7 illustrates how this can bedone.

A first module 26 is hinged to a second module 27 at hinge 28 it'svector V, being shown. The second module has been hinged so its vectorV2 extends at a new angle. Vector V2 is unique to its own module, sothat its own orientation in space is determined by the placement of themodule ahead of it. It is the function of this invention to place eachof the modules relationship to its neighbors to direct the totalstructure at its own position in the sequence. The first hinge link ismounted to supporting structure (not shown) to establish an origin forthe struts.

The cross-wise relationship between hinge links AB and CD, provides thefacility to direct these structures as disclosed. Even though they donot intersect, rotation around these axes provides the ability to directthe vector of a combination of two of them into any direction within thefields of the vector, to provide various shapes sinuous, twistingcircular and straight as desired.

For example, in FIG. 6, axis AB1 enables the module 21 to swing inmazimuth from side to side as shown by arrow 30. Adjustment inmelevation is attained by pivoting module 22 around axis A2B2. Then thevector from module 22 is determined by the initial position of axis AB1,and the position of module 22 around axis A2B2. The combination ofazimuth and elevation adjustment available at each pair of modulesenables the structure to be directed as desired in its field. This issimilar to, but not identical to artillery concepts. The cross-wise axesin this invention do not intersect, but it is equivalent to artilleryconcepts for the purposes of this invention.

As will be shown, the bearing structures at the apex joinders cannotonly be set manually in an adjusted position, but adjustment can beprovided by any suitable rotary motor M1 at the bearing structure, or bya linear motor M2 between appropriate apex joinders (FIG. 6). In thislater arrangement, a cable or turnbuckle can be used to hold an adjustedposition, all as schematically shown.

Frequently auxiliary equipment,(not shown), such as lights or rails willbe attached to the truss, perhaps using a clamp or other attachmentdevices at the apex joinders (nodes).

The bearing structure at the apex joinders is formed in twocomplementary shapes. Each joinder is provided with two of each shape,so disposed and arranged that the hinge link AB of one will fit andengage to hinge link CD of its neighbor.

As shown in FIGS. 10 and 11, bearing structures 30, 31 arecomplementary. Each includes a bearing face 32,33, a central fastener oraxial passage 34,35, and in the preferred embodiment an arcuate stop36,37, having a pair of shoulders 38,39 and 40,41 which engage at thelimits of permitted rotatability. They rotate in the same plane. Each isfixed to adjacent structures. When they meet in abutment the stop therotation The permitted rotatability is the difference between 360degrees and the total arcs of the steps. In the illustration, each stepis 120 degrees. The permitted rotation is 120 degrees. This is anoptional feature.

The two complementary apex joinders can readily be placed together, andheld together by fastener means that enable relative rotation, forexample a headed bolt and nut.

In use, after placing the hinge link of the first module, usually on amount that enables the module to rotate around it, the vector of thefirst module is established. Then the next module is attached—in linksAB in the link of the first module, and its vector is established. Thissequence continues for any number, usually three or more, until thetruss is completed. The apex joinders are tightened down at each step.

The relative orientation of successive modules can readily becalculated, so that the parts when delivered can be accompanied byinstructions for assembly.

If desired, indexing holes 50 can be provided to pass a pin through onepoint of the bearing structure into a hole 52 in the other so as readilyto establish the angle between the module at same established values.

When all of the links have the same length, the module will (whencompleted) be a regular tetrahedron with all of its faces equilateraltriangles. This is the most convenient and recommended situation.However, if the lengths of the spacer links are equal, but longer orshorter than the hinge link, the side faces will be isosceles ratherthan equilateral. This will still function and is within the scope ofthis invention The device can be made of any size and strength. Usuallythe links will be aluminum alloy tubings of appropriate diameter andwall thickness. The nodes are usually machined or cast metal.

This invention is not to be limited by the embodiments shown in thedrawings and described in the description, which are given by way ofexample and not of limitation, but only in accordance with the scope ofthe appended claims.

1. A module for joining into a sequence of complementary said modules toform a truss of selectable configuration, said module comprising: arigid hinge link; a first and a second apex joinder at a respectivefirst and second end of said hinge link; four rigid spacer links, afirst pair of said spacer links being rigidly attached to said firstapex joinder and the second pair of said spacer links being rigidlyattached to said second apex joinder; a third and a fourth apex joinder;one spacer link of said first pair and one spacer link from said secondpair extending from respective first and second apex joinders toconverge on and be rigidly attached to said third apex joinder; theother spacer links of said first and second pair extending fromrespective first and second apex joinders to converge on and be rigidlyattached to said fourth apex joinder; all of said apex joinders having arespective central axis of hinge rotation, the axes of said first andsecond apex joinders being coincident on a first rotation axis and theaxes of said third and fourth apex joinders being coincident on a secondrotation axis; said first and second rotation axes being skew to oneanother, and normal to each other in a plane that includes the mid-pointof said hinge link and the said second rotation axis; there being anunobstructed spacing between said third and fourth apex joinders forreception, engagement and rotation relative to a second module with asimilar hinge link, said first and second apex joinders facing axiallyaway from each other, and said third and fourth apex joinders facingaxially toward one another.
 2. A module according to claim 1 in whichthe lengths of all of said links measured between their respective apexjoinders are equal.
 3. A module according to claim 1 in which thelengths of all of said spacer links are equal.
 4. A module according toclaim 1 in which each said apex joinder includes one part of a bearingstructure.
 5. A module according to claim 4 in which said bearingstructure includes means to limit the extent of available rotation of acomplementary bearing structure.
 6. A module according to claim 4 inwhich the said part of the bearing structure of the first and secondapex joinders is complementary to the said part of the bearing structurethird and fourth apex joinders, whereby the first and second apexjoinders of another similar module will be received by the third andfourth apex joinders of this module to form a pair of joined-togethermodules.
 7. In combination: a first and a second module according toclaim 1; said hinge link of said second module fitting into said spacingbetween said third and fourth apex joinders of said first module, withthe respective apex joinders joined for rotation around the rotationaxis of said first module; said apex joinders provided with bearingstructure providing for relative rotation of said modules, includingmeans to hold said modules in an adjusted angular relationship to oneanother.
 8. A combination according to claim 7 in which said bearingstructure includes complementary shoulders on each of said apex joindersto limit the extent of rotational movement.
 9. A combination accordingto claim 7 in which indexing means is provided to hold the modulesangularly relative to one another at a pre-selected angle.
 10. Acombination according to claim 7 in which motive means is provided tochange the angular relationships of adjacent modules.
 11. A combinationaccording to claim 10 in which said motive means is an electricalrotating motor.
 12. A combination according to claim 10 motive means isa linear force member adapted to change the distance between the hingelinks of contiguous modules
 13. A truss comprising assembly of three ormore modules according to claim.1, interconnected according to claim 7.14. A truss comprising a combination according to claim 7, furtherincluding a structural mount to support and retain the hinge link of thefirst module.
 15. A truss according to claim 14-in which attachmentmeans is provided at at least one of said apex joinders for attachmentof objects to said truss.